I live in a lovely part of the countryside, and scattered around where I live (South Wales) there are at least half a dozen pillboxes. These are buildings that were built in WWII—designed as heavily fortified machine gun emplacements—and they formed defensive lines across southern and eastern Britain in case of a German invasion. They weren’t designed to stop the enemy advance, just slow it down. They were always built in line of sight of the next pillbox, and though many have now vanished, there are still lots of these overgrown, solid buildings, usually made of cast concrete and brick. They’ve always interested me.